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Ken Bassett Rascal Runabout - Plywood/Veneer Selection Advice Needed

I am nearing the task of applying a first layer of marine plywood to my Ken Bassett Rascal boat and then attach an outer layer of mahogany. Ken Bassett's plans outlined a 4mm marine Okoume plywood and a quarter inch outer layer of mahogany planks. I am looking for advice on a reputable company(s) to place an order for the marine plywood and the mahogany 1/4 inch planks. The mahogany planks could be expensive. So, I would like to be able to compare alternatives for the plywood and mahogany planks. Is there a suitable substitute for the 1/4 mahogany perhaps a veneer?

Please share your thoughts and suggestions on:
- Companies that ship marine 4mm plywood and 1/4" mahogany planks
- Alternatives to Okoume plywood and or 1/4 " mahogany planks
- Types of material others have used that built a Rascal runabout or similar boat and had success
- Methods to attached the plywood and planks (staples, epoxy, vacuum bagging, combinations, etc.)

I used okoume ply and 1/4 mahogany for mine but I resawed the mahogany myself. I’d look for a local place to resaw 8/4 for you. If they have a good saw waste will be minimal. That was the most economical solution for me.
I would think there would be a local supplier of ply. I bought mine from a place in Maryland (??) but went in with someone on a larger order to make shipping reasonable. It’s been a long time since I bought the ply so the details are fuzzy.

For fasteners I used stainless steel staples and specified. If i did it again I would probably use raptor plastic staples with epoxy or staple through plastic banding and remove the staples rather than leave in place.

I am nearing the task of applying a first layer of marine plywood to my Ken Bassett Rascal boat and then attach an outer layer of mahogany. Ken Bassett's plans outlined a 4mm marine Okoume plywood and a quarter inch outer layer of mahogany planks. I am looking for advice on a reputable company(s) to place an order for the marine plywood and the mahogany 1/4 inch planks. The mahogany planks could be expensive. So, I would like to be able to compare alternatives for the plywood and mahogany planks. Is there a suitable substitute for the 1/4 mahogany perhaps a veneer?

Hi again Tony. For starters, I agree with all of what Tom said in his posts. I will add a few more comments.

With regard to veneers, I suppose that may work, but you would want another layer of something more substantial on top of the first layer of marine plywood. Maybe a second layer of plywood, and then a veneer. I did this on my boat in the forward bottom section as I could not get the 1/4" mahogany to bend properly. So, I put down a second layer of marine plywood (3mm) and then used 1/8" planks. In the end, you cannot see this anyway. Actually, the plans call for 2 layers of marine plywood on the bottom of the boat. Overall, I think the 1/4" mahogany planks set in epoxy on top of the plywood is a very good method, very strong, and looks great when finished. If you do some searches on this forum you should find examples of some other Rascals and comments on some of the construction choices.

Please share your thoughts and suggestions on:
- Companies that ship marine 4mm plywood and 1/4" mahogany planks
- Alternatives to Okoume plywood and or 1/4 " mahogany planks
- Types of material others have used that built a Rascal runabout or similar boat and had success

I think I ordered the okume from Harbor Sales, but this was many years ago. Bottom was 2 layers of 4mm and the topsides and deck were 1 layer of 3mm okume covered w/ 1/4" planks. You may be able to save money on shipping if you get them to rip the panels into 1 ft. or 2 ft. wide sections. You can find other sources on Google and/or check with some of the kayak-building websites as they generally use the same types of plywood. Look for the okume that is registered as 1088 (if memory serves correctly). I would think that someone would have this type of okume around New Orleans, but be sure it is marine grade 1088.

With regard to the planking, the plans called for genuine mahogany (Honduran). I could not find this around where I live except for small boards and it was pretty expensive. However, a couple of the local lumberyards carry African mahogany and this is what I used for the planking as well as some other parts like the chines, etc. I typically bought 4/4 boards and found a local guy who resawed each board so I got 2 planks out of each 4/4 board. For the decking, the planks were only 4" wide so I resawed those myself on a table saw. Then plane them down to 1/4" thickness.

Other than mahogany, I did consider Spanish cedar as it looks very similar. Spend some time looking around at some of the "hardwood" lumber yards around your area. Sapele is another choice but may be heavier and I don't recall how the price compares to African mahogany.

As Tom said, the plastic staples may be a good alternative. I used the stainless staples as called for in the plans and had no issues with those. You will have to fill the holes where the staples are countersunk. Or I suppose you could pull them out. I think there was one Rascal on here that used vacuum bagging (user=Audioten), but I don't have experience with that at all.

NC coastal boatbuilders use large quantities of occoume ply and hardwood lumber so Its not all that hard to find. Many mills can supply veneer of any thickness and its not difficult to cut your own if you have a bandsaw. If you will be painting the bottom, ply is a better choice to the chines than veneer and the expensive veneer can be used for the topsides and decks. I've had the pleasure of driving a Rascal and its a hoot plus beautiful as well.

I used a stainless plate on the back of the transom here and an aluminum angle on the front to keep the motor from twisting off, which they are prone to do in rough handling. Many have had clamped motors twist off the transom and go into the drink. You will probably be using 50HP or more and it will be through bolted. Drill large holes and fill with epoxy which will be drilled for the mounting bolts. No need for other reinforcement.

I used a stainless plate on the back of the transom here and an aluminum angle on the front to keep the motor from twisting off, which they are prone to do in rough handling. Many have had clamped motors twist off the transom and go into the drink. You will probably be using 50HP or more and it will be through bolted. Drill large holes and fill with epoxy which will be drilled for the mounting bolts. No need for other reinforcement.

By "transom support" do you mean the transom knee, or something else? I do recall one builder on here who fabricated the transom knee out of steel but this seems like overkill to me. I used ash as called for in the plans and have not had any issues.

I don't have a photo of that but it was a 1/8 X 1 1/2 X 1 1/2 with one side cut down to allow the clamps to go over. Nothing special.

I don't use triangle transom knees for support as I think they are a holdover from long ago and not as good as other means. I reinforced the transom with the deck, carlin and inwhale in this case as well as a strong transom top across from side to side. An outboard levers the transom in at the bottom and out at the top. A knee does not do a good job of resisting these forces and has the most strength opposite to what is needed. In addition, a knee can exert a lifting force on the bottom causing a hook in the bottom which is not a good thing. With a powerful motor, this can drive the bow down causing the boat to be wet.

I realize this goes against common practice, bit my analysis of forces says its true anyway. The bottom and keel/keelson does a good job of resisting forward thrust of the motor. Side decks, aft topsides and other longitudinal members resist the aft motor force where its most needed at the top of the transom and does not distort the bottom at all. Good engineering practice must be used in any case.

Boat looks great! Lots of good advice so far, I'll add my 2 cents. I vacuum bagged the mahogany bottom and side planking. I used a cheap Craftsman pancake air compressor with a venturi (from JoeWoodworker.com) to pull a vacuum (got the plastic there too); I believe I used West System yellow tape to seal. Turned out okay for a beginner with no experience, but it was a frantic/hectic job trying to plug air leaks with a real (or imagined) time constraint . I planked the sides with the boat upside down, starting at the chine and gluing each successive plank down to shear. If I had to do it again, I'd flip the boat right side up and plank from chine up to shear and let gravity help keep new plank tight to the plank already glued, if that makes any sense. It was a nightmare trying to come up with clever ways to fixture the new plank inside the bag to stay up tight to the plank above.

I will add that my inspiration to vacuum bag was from volume 24, 2006 of Epoxy Works in an article written by Steve Gembrowski, link here https://epoxyworks.com/index.php/the-rascal-project/. He goes into great detail building his Rascal and using vacuum bagging. A great resource.

With respect to transom bracing, just build to the specs outlined in the plans. My engine puts out an estimated 85HP at prop and weighs roughly 265lbs dry, the CMC tilt/trim unit adds another 60lbs - the boat handles the power and weight easily. She's just as happy to cruise along at 25mph as she is at 60+mph.

Boat looks great! Lots of good advice so far, I'll add my 2 cents. I vacuum bagged the mahogany bottom and side planking. I used a cheap Craftsman pancake air compressor with a venturi (from JoeWoodworker.com) to pull a vacuum (got the plastic there too); I believe I used West System yellow tape to seal. Turned out okay for a beginner with no experience, but it was a frantic/hectic job trying to plug air leaks with a real (or imagined) time constraint . I planked the sides with the boat upside down, starting at the chine and gluing each successive plank down to shear. If I had to do it again, I'd flip the boat right side up and plank from chine up to shear and let gravity help keep new plank tight to the plank already glued, if that makes any sense. It was a nightmare trying to come up with clever ways to fixture the new plank inside the bag to stay up tight to the plank above.

I will add that my inspiration to vacuum bag was from volume 24, 2006 of Epoxy Works in an article written by Steve Gembrowski, link here https://epoxyworks.com/index.php/the-rascal-project/. He goes into great detail building his Rascal and using vacuum bagging. A great resource.

With respect to transom bracing, just build to the specs outlined in the plans. My engine puts out an estimated 85HP at prop and weighs roughly 265lbs dry, the CMC tilt/trim unit adds another 60lbs - the boat handles the power and weight easily. She's just as happy to cruise along at 25mph as she is at 60+mph.

Keep up the good work, looking forward to more progress photos!

Pete

Thanks for the advise and encouragement. It's my first build. I am making my 4th trip to the wooden boat school in Maine this August. Great to be around like minded boat lovers.

By "transom support" do you mean the transom knee, or something else? I do recall one builder on here who fabricated the transom knee out of steel but this seems like overkill to me. I used ash as called for in the plans and have not had any issues.

Dave

I spoke to Ken Bassett about a year ago and he actually recommended an aluminum transom knee in retrospect. I guess newbie builders like myself may not have the knowledge to properly support the transom.

I think what you have is 100% fine. The transom is a full 2 1/4 inches thick and is attached to the keelson, all of the battens, the sheer clamps, the chines, and then the layers of plywood and planking. And also the transom knee is bolted and epoxied to the transom and the keelson.

Thanks for the advise and encouragement. It's my first build. I am making my 4th trip to the wooden boat school in Maine this August. Great to be around like minded boat lovers.

Not sure if I will be in NH at the time but that's where my rascal lives. If I'm around you are welcome to come by. I'm an hour or so west of Portland.

As far as the knee, I'd built it to the plan specs. I know he has used an aluminum welded knee since, but I don't really see the need. There is plenty holding that transom in. I'm not exactly easy on my boat and no issues yet. I'm not running as much power as Peter but I've had it full out in some very rough chop both here and on winnepesaukee. The boat will take more than you can.